Positions are apparent positions (where they appear in the sky at the
time), not true positions. Planet and Moon positions are from NASA/JPL
ephemeris files. This online ephemeris is provided for free.
Neither JPL nor ephemeris.com make any warranty as to
the suitability of their ephemeris data for any purpose.

Sedna positions are from preliminary orbital elements published by the
Harvard-Smithsonian Center for Astrophysics, and are only approximate
over long periods of time.